Print PageBiodiversity is rapidly declining worldwide, and there is consensus that biodiversity declines can lead to subsequent declines in ecosystem functioning and services. It remains unclear, though, whether few or many of the species in an ecosystem are needed to sustain the provisioning of ecosystem services. It has been hypothesized that most species would promote ecosystem services if many times, places, functions, and environmental change scenarios were considered; however, no previous study has considered all of these factors together. We combined data from 17 grassland biodiversity experiments, and identified the species that influenced ecosystem functioning in 557 functional contexts (where a functional context is defined as the measurement of one function at one time and place, under one environmental change scenario). Species were considered to promote ecosystem functioning in a context if they had effects in the direction that would usually be considered desirable from an ecosystem services perspective.
Results/Conclusions
We found that 84% (123 of 147) of the grassland plant species included in these studies promoted ecosystem functioning in at least one context. Different species promoted ecosystem functioning during different years, at different places, for different functions, and under different global change scenarios. Furthermore, the species needed to provide one function during multiple years were not the same as those needed to provide multiple functions within one year. Our results indicate that even more species will be needed to maintain ecosystem functioning and services than previously suggested by studies that have either: (i) considered only the number of species needed to promote one function under one set of environmental conditions, or (ii) separately considered the importance of biodiversity for providing ecosystem functioning across multiple years, places, functions, or environmental change scenarios. Therefore, although species may appear functionally redundant when one function is considered under one set of environmental conditions, many species are needed to maintain multiple functions at multiple times and places in a changing world.
